Apparatus for simultaneously stretching and falsetwisting yarn



June 25, 1963 J. c. DEELEY ETAL 3,094

APPARATUS FOR SIMULTANEOUSLY STRETCHING AND FALSETWISTING YARN FiledJune 27. 1960 Inventors n/ofl/l coA/n/ D5545) Joy/v ALE W544 m fiwmzsspolyam-ide or a polyester.

3,094,834 Patented June 25, 1963 ice ' Claims priority, applicationGreat Britain July 3, 1959 3 Claims. (Cl. 57-55.5)

This invention relates to crimped yarn and more particularly to yarncrimped by means of setting a twist therein and to processes for themanufacture thereof.

The present yarn consists of continuous filaments and is composed of asynthetic linear polymer, for example, a The filaments may consistwholly of polyhexamethylene adipamide, but other synthetic linearpolymers may form the material of the filaments, for instance,polyureas, e.g. polyhexamethylene urea, polyurethanes, e.g. polybutyleneglycol hexamethylene dicarbamate, polyesters, e.g. polyethyleneterephthalate, stereo-specific polyolefines, e.g. polypropylene, or thefollowing polyamides namely, polyhexamethylene sebac- "amide,poly-kappa-aminoundecanoic acid, poly-epsilon- Such yarn is accordinglymanufactured commercially on a large scale, the high tenacity beingattained by submitting the filaments to a process of drawing while theyare in the solid state, a process frequently referred to ascold-drawing. Thus the filaments, in their undrawn condition after beingsolution-spun or melt-spun from the required polymer, are elongated inthe solid state, commonly by passage between two pairs of rolls, thesecond pair revolving faster than the first. Between the rolls thefilaments may, if desired, pass round a snubbing pin so as to locate thepoint at which drawing takes place.

For many uses the yarn is required in a crimped condition, and one knownmethod of crimping comprises setting the yarn by heat while in afal=se-twisted condition. It has furthermore been proposed to makecrimped yarn by taking synthetic polymer yarn in its undrawn condition,i.e. as spun, and false-twisting and drawing it simultaneously whilehot. In this way the yarn is elongated while temporarily twisted and ata raised temperature, and when the tension is released, the filamentsbecome crimped or curled. The yarn then possesses a pleasant fullness.Thus, the filaments after being drawn While hot and in a false-twistedstate, have become potentially crimpable, which is defined as meaningthat they will assume a crimped configuration on being relaxed. Theprocess of relaxation or crimping may be promoted by the application ofheat.

Whereas sundry forms of false-twisting apparatus are known, a novelmethod of inserting the false-twist during.

is most eflective in imparting a false-twist thereto, so

that the yarn is drawn while in an intensely false-twisted condition,and subsequently relaxing the yarn.

Accordingly this invention relates to a process and apparatus tor theproduction of crimped yarn, comprising drawing undrawn or incompletelydrawn synthetic linear polymer multifilament yarn between a feed rolland a draw roll provided with a flange, the yarn being heated and guidedon to the flange of the draw roll in a direction making an acute anglewith the axis thereof whereby the yarn makes frictional contact withsaid flange, which has a contour constituting a surface of rotationgenerated and defined by a curved geodesic line connecting the points atwhich the yarn makes and breaks contact therewith, and which rapidlyrotates the yarn about the axis thereof, imparting false twist to thehot yarn and making it potentially crimpable as hereinbefore defined,and subsequently relaxing the yarn in order to crimp it.

The invention includes the potentially crimpable yarn made describedabove, and its conversion into crimped yarn before or after fabricationinto fabric or textile articles by weaving or knitting. The inventionalso comprises crimped yarn made by the above process and textilearticles knitted or woven therefrom.

Thus, the operation of weaving or knitting may be conveniently carriedout on the potentially orimpable yarn and the crimp developed byrelaxing the resulting fabric or textile articles made therefrom byboiling in water. The employment of the yarn in the potenatiallycrimpable but uncrimped state in this way has the advantage that theaction of the textile machinery is not impeded by the presence of thecrimps. Nevertheless, it is desirable that the fabric structure be of aloose or open character, otherwise the development of the crimps in thefabric will be prevented or hindered.

The undrawn or incompletely drawn yarn employed as starting materialshould preferably possess no or only a low twist, so that the aforesaidterm yarn is to be understood to include twistless yarn.

Preferably in the present process the yarn is passed round a snubbingpin positioned between the feed roll and the draw roll. In this case thefalse-twisted portion of the yarn extends from the draw roll and flangeto the snubbing pin.

Any suitable external source of heat may be employed for heating theyarn. For example, the snubbing pin (if used) may be heated, or the yarnmay be caused to run over a hot plate. Some other means for heating theyarn are hot nitrogen, steam, infra-red radiant heat, hot molten metalor a high frequency electrical field. It is evident that the temperaturereached must not be so high as to melt the polymer, and the meltingpoints of the polymers already mentioned above are therefore now quotedas a guide:

Polyhexamethylene adipamide 248 Polyhexamethylene urea 270 Polybutyleneglycol hexamethylene dicarbamate 178 Polyethylene terephthalate 255Stereospecific polypropylene 165 Polyhexamethylene sebacamide 209Poly-kappa-aminoundecanoic acid 187 Poly-epsilon-caprolactam 214 Ifdesired, the heat treatment of the yarn may take place while a swellingagent for the polymer is present.

To obtain a given degree of setting of the deformations, a lowertemperature is normally needed when a swelling agent is employed.Examples of swelling agents for use with polyhexamethylene adipamide arewater, steam, aniline, and alcohols such as methyl alcohol, ethylalcohol,

isopropyl alcohol, glycol, glycerol.

While under normal conditions of working, the draw 7 roll issufliciently cool for the success of the present process, the draw rolland/ or the yarn in the neighbourhood of the surface thereof may bedeliberately cooled, if desired, for example, by a jet of cold airdirected thereon, or by circulating cooling fluid within the draw roll.The

importance of the temperature of the yarn at that portion thereof wherethe false twist is no longer present (i.e. on the draw roll) lies in thefact that the deformations already set in the yarn could be annihilatedunder the influence of suificient heat and tension.

The feed roll or the snubbing pin (if used) may conveniently be offsetwith reference to the draw roll so that the yarn approaches the flangemaking an acute angle with the axis thereof. The necessary acute anglemay also be obtained by suitably directing the yarn by guides.Provided'that this angle be not so small as to incur the risk ofbreaking the yarn, it has been observed that in general, the smaller theangle, the better the quality of the resulting crimp. The greater thediameter of the flange, the higher the maximum peripheral speed where itmakes contact with the yarn, and consequently-the greater the possibledegree of false-twist.

The flange may be fabricated of any convenient material capable ofwithstanding abrasion, as far as possible, while yet apt to gain a gripon the yarn so as to diminish slippage. The following materials forinstance, may be quoted: glass, ceramics, vulcanite, polyamides,polyurethanes, for instance, polybutylene glycol hexamethylenedicarbamate, alumina, Carborundum, stainless steel, but the optimumdegree of smoothness (or roughness) of the surface depends on thesubstance chosen. Resilient materials are particularly effective forthis purpose. Thus, natural and artificial rubbers and other elastomersare very useful, e.g. polybutadiene, butadiene-methyl-methacrylatecopolymer, polychloroprene, butadiene-acrylonitrile copolymer,butadiene-styrene copolymer; polysulphide rubbers, e.g. polyethylenetetrasulphide; polymers derived from isobu-tylene, e.g. polyisobutylene,isobutylene-isoprene copolymers; polyacrylic esters, e.g. ethylacrylate-2- chloroethyl vinyl ether copolymer; silicones e.g.polydimethyl-silicone. Suitable polyester-urethanes,polyesteramide-urethanes and polyether-urethanes may likewise beemployed. Polychloroprene has been found especially effective. The Shorehardness of the elastomer may vary between 55 and 86 but the range 75 to85 is preferred.

The contour of the flange constitutes a surface of rotation generatedand defined by a curved geodesic line connecting the points at which theyarn makes and breaks contact therewith, and accordingly the flange maybe either convex, or flat (i.e. conical) or somewhat hollow, since theyarn does not traverse the flange radially but follows an obliquecourse. It is preferred that the flange be convex.

The flange may be constructed so as to form with the draw roll one pieceof material or may be separate, and is conveniently detachabletherefrom. When an elastomer is used, this can take the form of a sleevefitting over a steel flange. The sleeve, for example, a rubber sleeve,may then, when worn, easily be replaced by a new one.

It will be apparent therefore that the present process may readily becarried out on a conventional drawing machine after relatively minormodification thereof comprising fitting a suitable flange. Moreover thepresence of thefiange does not interfere with the normal method ofthreading the yarn on to the machine when commencing drawing. Althoughthe speed of drawing may have to be reduced somewhat in order to obtainthe best crimped yarn, crimp of acceptable quality may be got at therelatively high speeds of drawing employed commercially.

The process of crimping on relaxation as already indicated may beadvanced or hastened by the application of heat, for instance, bysubmitting the potentially crimpable yarn, after releasing the tension,to the action of hot air and steam. This may be done before or after thepotentially crimpable yarn has been twisted and/ or converted into afabric. It is important to note, however, that when this process ofcrimping is accelerated by the application of heat, the temperature mustnot be raised too rapidly, especially if the yarn is in the form of afabric, otherwise 4 the yarn may become set before there has been anopportunity for the crimp to develop. This is because the eflect of heatis to set the yarn, as is well-known.

If desired, the tension need not be wholly released when heat is appliedto develop the" crimp, since it may be preferred to allow the yarn toretract only to a limit extent. This may be conveniently effected byoverfeeding the yarn by a prescribed amount as it proceeds from the drawroll to some forwarding nip rolls, provision being made for the yarn totraverse a hot zone situated between the draw roll and the forwardingrolls. Instead of the aforesaid hot Zone, the forwarding rollsthemselves may be heated.

The heat treatment applied to develop the crimp may thus serve also toset it adequately, or else, a subsequent heat-setting can be applied ifdesired. In the latter case the crimped yarn produced, or fabric ortextile articles, woven or knitted therefrom, are submitted to a settingtreatment by means of heat and optionally water or steam or anotherswelling agent. The effect of swelling agents in reducing thetemperature needed for a given degree of setting, has already beennoticed. The degree of setting necessary or desirable depends, interalia, on the finishing or after-treatment, e.g. dyeing, which thefilaments are likely or intended to receive.

The crimped yarn of this invention is very suitable for knitting intounderwear, or hose, and also for weaving into fabric having anattractive warm full handle. The present process moreover has theadvantage that the drawing and crimping of the yarn are accomplishedsimultaneously in one continuous operation with economy in productioncosts.

Further objects, advantages and novel features of this invention willbecome apparent in the specification and claims, taken in connectionwith the accompanying drawlngs:

FIGURE 1 is a diagrammatic perspective view of an apparatus according tothis invention;

FIGURE 2 is a side elevation view of the draw roll and flange in FIGURE1; and,

FIGURE 3 is a front elevation view of the draw roll and flange shown inFIGURES 1 and 2.

Reference is now made to the accompanying drawings, wherein there isshown a feed roll 1 and an electrically heated snubbing pin 2 spacedapart therefrom. Mounted below the pin 2 is a draw roll 3 being in aplane generally perpendicular to the snubbing pin 2, as best shown inFIG- URE 2.

There is provided a separating roll 4 axially separated from the axis ofthe draw roll 3, the draw roll 3 including a flange 5. Mounted below theflange 5 of the draw roll '3 is a conventional bobbin for winding theyarn 7.

The yarn 7, as best shown in FIGURE 1, is passed once round the feedroll 1, twice round the snubbing pin 2 and thence to the draw roll '3with flange 5. The heated snubbing pin is set off from the draw roll, ascan be seen in FIGURE 2, so that the yarn rubs on the flange 5 and hasimparted to it a 2 false twist. The yarn then passes thrice round thedraw roll 3 and separator roll 4, and is wound up on bobbin 6.

Example 1 The materials used in the above apparatus are as follows:

Feed and draw rolls Chromium plated steel. Snubbing pin materialAlumina.

Temperature of snubbing pin C.

Flange on draw roll Polybutadiene rubber. Flange hardness Shore hardness80.

The yarn used is multifilament polyhexamethylene adipamide yarncontaining 34 filaments and possessing a denier of 210 in the undrawnstate. The mechanical draw ratio is 3 and the peripheral speed of thedraw roll 400 feet per minute. The wind up bobbin revolves 4000 timesper minute.

Sundry dimensions appertaining to the draw roll and flange are:

Inches Diameter of draw roll 3 /8 Diameter of flange 8 Yarn distancebetween draw roll and snubbing pin 3 Offset distance between draw rolland snubbing pin 2 Example 2 Example 1 is repeated but two yarns areused and the apparatus is duplicated, the two draw rolls and flangesbeing arranged back to back on the same shaft. In this way one yarnacquires a Z false twist and the other yarn an 8 false twist. Theresulting yarns are doubled together and submitted to a relaxationtreatment by passage through a bath of boiling water. A pleasantlycrimped yarn is obtained in this way.

Example 3 In this example the conditions of Example 1 are altered asstated below, those conditions which are unmentioned remaining the same.

Snubbing pin material Chromium plated brass. Temperature of snubbing pin165 C.

Flange material Polychloroprene. Flange hardness Shore hardness 86.Flange diameter 3%. inches.

Mechanical draw ratio 2%.

Peripheral speed of draw roll 800 ft. per minute. Yarn distance betweendraw roll and snubbing pin 5 /2 inches. Offset distance between drawroll and snubbing pin 2% inches. Acute angle between yarn and axis offlanged roll 60.

When relaxed the resulting yarn becomes well crimped. Thus if 120 yardsof the yarn be wound into a hank on a reel having a circumference of 54inches and a 3% gram weight hung on the hank, the length thereof, as ithangs, is 27 inches. When plunged into a bath of water at 60 C., thehank contracts from 27 inches to 7.4 inches owing to the development ofthe crimp.

It is found that the speed of drawing can be increased to 1260 feet perminute with little deterioration in the resulting crimp.

Example 4 Example 3 is repeated except that the speed of the draw rollis reduced to 600 feet per minute and the flange diameter increased to5%". A similar crimped yarn results.

6 Example 5 Polycaprolactam yarn comprising 6 filaments and having atotal denier of 342 is drawn by means of the apparatus described in thepreamble at a draw ratio of 4.3 and drawing speed of 400 feet per minuteover a chromium plated brass snubbing pin maintained at 165 C. The drawroll carries a polychloroprene flange of 3% inches diameter andpossessing a Shore hardness of 88. The yarn as it is drawn rubs againstthe rotating flange approaching it at an angle of 45 with the axisthereof and thereby acquires false twist. After relaxation a goodcrimped yarn is obtained.

Example 6 Stereospecific polypropylene yarn having 6 filaments and atotal denier of 78 is drawn in exactly the same way as described inExample 4 except that the draw ratio is reduced to 2 and the temperatureof the snubbing pin to C. A yarn with a tight helical crimp is producedon relaxation.

From the foregoing description of the various embodiments of thisinvention, it is evident that the objects of this invention, togetherwith many practical advantages are successfully achieved. Whilepreferred embodiments of my invention have been described, numerousfurther modifications may be made without departing from the scope ofthis invention.

Therefore, it is to be understood that all matters herein set forth orshown in the accompanying drawings are to be interpreted in anillustrative, and not in a limiting sense.

What we claim is:

1. A yarn drawing apparatus comprising means for supporting a yarnpackage; a feed roll spaced apart from said package; a draw rollincluding a hub and a convex peripheral flange, said flange surfacebeing defined by a surface of rotation generated by a curved geodesicline connecting the points at which the yarn makes and breaks contacttherewith; a snubbing pin spaced apart from said feed rolls andpositioned in offset relationship with respect to the plane of said drawroll flange and operative to guide yarn therefrom in contact with saiddrawn roll flange surface in a direction defining an angle relative tothe axis of said draw roll flange which is a maximum of approximately60; means for heating the yarn prior to passing the same past saidflange surface, the ratio of said hub to said peripheral flange beingsufficient to produce a false twist of at least 40 turns per inch.

2. Apparatus defined in claim 1 wherein said yarn heating means isoperative to heat said snubbing pin.

3. Apparatus defined in claim 1 wherein said flange is composed of anelastomer having a Shore hardness between 55 and 86.

References Cited in the file of this patent UNITED STATES PATENTS2,410,419 Bellezza Nov. 5, 1946 2,590,374 Brown Mar. 25, 1952 2,936,567Russell et al May 17, 1960 2,943,433 Van Dijk July 5, 1960

1. A YARN DRAWING APPARATUS COMPRISING MEANS FOR SUPPORTING A YARNPACKAGE; A FEED ROLL SPACED APART FROM SAID PACKAGE; A DRAW ROLLINCLUDING A HUB AND A CONVEX PERIPHERAL FLANGE, SAID FLANGE SURFACEBEING DEFINED BY A SURFACE OF ROTATION GENERATED BY A CURVED GEODESICLINE CONNECTING THE POINTS AT WHICH THE YARN MAKES AND BREAKS CONTACTTHEREWITH; A SNUBBING PIN SPACED APART FROM SAID FEED ROLLS ANDPOSITIONED IN OFFSET RELATIONSHIP WITH RESPECT TO THE PLANE OF SAID DRAWROLL FLANGE AND OPERATIVE TO GUIDE YARN THEREFROM IN CONTACT WITH SAIDDRAWN ROLL FLANGE SURFACE IN A DIRECTION DEFINING AN ANGLE RELATIVE TOTHE AXIS OF SAID DRAW ROLL FLANGE WHICH IS A MAXIMUM OF APPROXIMATELY60*; MEANS FOR HEATING THE YARN PRIOR TO PASSING THE SAME PAST SAIDFLANGE SURFACE, THE RATIO OF SAID HUB TO SAID PERIPHERAL FLANGE BEINGSUFFICIENT TO PRODUCE A FALSE TWIST OF AT LEAST 40 TURNS PER INCH.